Rivera, who likely will take the job and be announced as coach in the next few days, is in North Carolina to meet with Panthers owner Jerry Richardson. Rivera is one of four men to interview for the job, but he's the first candidate to speak directly with Richardson.
"Could something get done quickly? Sure," a source with knowledge of the situation said. "But there's also a possibility it doesn't happen at all."
None of those three have received second interviews. That makes Rivera, a former linebacker with the Chicago Bears and a member of that franchise's Super Bowl-winning team in 1985, the front-runner as he seeks his first NFL head-coaching job.
Rivera's initial meeting with team officials went well, and there is potential for a deal to be struck, pending the second sit-down and ownership's approval.
If Rivera is hired, Manusky will be considered for the Panthers' defensive coordintor job. He has ties to Hurney.
Ryan, currently the Browns' defensive coordinator, also would be a finalist for that job. Ryan's father, Buddy, coached Rivera in Chicago.
Ron Turner (now an assistant with the Indianapolis Colts, but he was offensive coordinator in Chicago when Rivera was there) and Chargers tight end coach Rob Chudzinski would be top candidates to become the Panthers' offensive coordinator, according to a league source. Bears assistant special teams coach Chris Tabor would be a top candidate for the Panthers' special-teams coaching job, according to sources.
Rivera has plenty of experiencing interviewing for head-coaching jobs, with Carolina marking the ninth team to talk to him over the years.
The Panthers are looking for the fourth coach in their 16-year history after Richardson decided not to bring back Fox after his ninth season ended with an NFL-worst 2-14 record.
Richardson said last week that while he was most concerned with his team's league-worst offense, it wouldn't stop them from hiring a defensive-minded coach as long as he had a strong offensive coordinator and quarterbacks coach.
"We're putting a very high priority on the offense, and that can be accomplished without having an offensive head coach," Richardson said.
The son of a U.S. Army officer, Rivera lived in Germany, Panama, Washington, Maryland and California growing up and has a diverse coaching background, working with both the 3-4 and 4-3 defensive schemes.
The Associated Press contributed to this report.